1. Field
The following description relates to a multiport amplifier, which is used for a communication satellite relay system and functions to control output power, and more particularly, to a multiport amplifier capable of automatically calibrating phase and amplitude mismatches caused in circuit configuration and environment.
2. Description of the Related Art
A multi-beam antenna system capable of providing narrow beams having a high antenna gain within service coverage has widely been employed as a payload system of communication and broadcasting satellites because the multi-beam antenna system has excellent effective isotropic radiated power (EIRP) and a high gain-to-noise temperature ratio (G/T).
A multi-beam antenna system has broadly adopted a multiport amplifier capable of controlling output power based on operation conditions. The multi-beam antenna system using the multiport amplifier may provide communication and broadcasting services using multiple spot beams within service coverage. The multi-beam antenna system may flexibly allocate high power to a region that requires higher EIRP due to a rainfall or a jump in communication service.
In addition, since high-power amplifiers, which may have the highest failure rate among components for satellite relay systems, are used in parallel, the multi-beam antenna system may be configured using a smaller number of high-power amplifier redundancy units than a conventional satellite relay system.
Operating principles of a multiport amplifier may be established only when connection components, such as hybrids, high-power amplifiers, and other transmission lines, perform ideal operations. When an actual multiport amplifier is embodied, there may be a difference in output powers of the hybrids, and an error in phase may occur.
In the high-power amplifiers, an output signal may have a different phase according to the magnitude of input power due to nonlinearity. When connection components, such as transmission lines, are not manufactured to have the same size and shape, variations in the magnitude and phase of signals may occur.
To recover the variations in the magnitudes and phases of the signals, a magnitude/phase adjusting circuit may determine magnitudes and phases of signals so that a multiport amplifier system is configured to optimize actual performance of the respective components when a multiport amplifier system is implemented.
However, when the performance of components constituting the multiport amplifier system varies due to variations in environmental conditions, such as degradation of the components or a variation in temperature, the multiport amplifier cannot remain optimized in terms of performance.